Biomaterial corrosion resistance

Next-generation metallic biomaterials include porous titanium alloys and porous CoCrMo with elastic moduli that more closely mimic that of human bone nickel-titanium alloys with shape-memory properties for dental braces and medical staples rare earth magnets such as the NdFeB family for dental fixatives and titanium alloys or stainless steel coated with hydroxyapatite for improved bioactivity for bone replacement. The corrosion resistance, biocompatibility, and mechanical properties of many of these materials still must be optimized for example, the toxicity and carcinogenic nature of nickel released from NiTi alloys is a concern. ... 

Okazaki, Y, Rao, S., Ito, Y, and Tateishi, T. Corrosion resistance, mechanical properties, corrosion fatigue strength and cytocompatibUity of new Ti alloys without Al and V. Biomaterials, 19,1197-1215 (1998). 

Considering the testing methods used to determine the main requirements which must be fulfilled by biomaterials, i.e. corrosion resistance, biocompatibility, bioadhesion and biofunctionality, it is obvious that only the measurement of the mechanical properties, including fatigue (biofunctionality), will supply objectively comparable results because these testing methods are standardized. 

Hendry, J. A. and Pilliar, R. M., The Fretting Corrosion Resistance of PVD Surface-Modified Orthopedic Implant Alloys, Journal of Biomedical Materials Research (Applied Biomaterials), Vol. 58, 2001, pp. 156-166. 

Gebeau, R. C. and Brown, R. S Corrosion Resistance and Strength of Biodur 108 Alloy, A Nickel-Free Austenitic Stainless Steel, Structural Biomaterials for the 21st Century, M. Niinomi, et. al. Ed., The Minerals, Metals and Materials Society, 2001, pp. 157-164. 

The results of extensive corrosion testing, biocompatibility studies, and clinical evaluation have been used to select the corrosion-resistant metals and alloys that are in use as implants today. In addition, there are new materials being introduced as well as modifications of the currently used ones. Additional information on the biological and chemical reactions at the body/biomaterial interface would be useful in determining short- and long-term effects on the body and in pref>aring the biomaterial for its intended use. 

NBE-PEO macromonomers providing two distinct properties. Gentamicin (GS)-terminated macromonomer 18b aimed to provide antibiotic properties in an acidic medium, while carboxylic acid-terminated macromonomer 18c enabled the grafting of the nanoparticles onto biomaterial surface. After the transfer of the particles in water, the controlled release of GS at acidic pEl was demonstrated by breakage of the imine bond as well as by the efficient antibacterial activity using S. epidermidis as the bacterial strain. Scheme 2.7. These double-functionalized nanoparticles were grafted onto a titanium-based alloy, which is a preferred biomaterial for bone implants because of its biocompatibility, mechanical strength, and corrosion resistance [32]. The particles were covalently linked... 

The most appropriate interpretation of biocompatibility for PE biomaterial applications is that the biocompatibility be defined in terms of the success of a device in fulfilling its intended function. For example, for a hip joint prosthesis, one must take into consideration the fatigue resistance of the device, its corrosion resistance, the distribution of the stresses transferred to the bone by the device, the solid angle of mobility provided, and the overall success of the device in restoring a patient to an ambulatory state. The performance of a hip joint prosthesis might also be assessed in terms of the tissue reaction to acetabular cup. The performance of individual materials is sometimes referred to as biocompatibility and sometimes as bioreaction . Hardness, shape, porosity, and specific implant site are very important [58]. 

Abstract There is enormous interest in nanostructuied biomaterials as they can stimulate tissue-biomaterial interaction more effectively. Research is focused on developing advanced nanostructured biomaterials. The major strategies include fabrication of nanocomposites, surface nanostructuring and nanostructured coatings. A potential issue of concern in terms of biocompatibility is the corrosion resistance of the modified biomaterials. 

Biomaterials. Just as stem designs have evolved in an effort to develop an optimal combination of specifications, so have the types of metals and alloys employed in the constmction of total joint implants. Pure metals are usually too soft to be used in prosthesis. Therefore, alloys which exhibit improved characteristics of fatigue strength, tensile strength, ductihty, modulus of elasticity, hardness, resistance to corrosion, and biocompatibiUty are used. 

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